In the making of hollow plastic containers, such as drums, it is desirable to provide an insert in a wall of the container which is adapted to receive a removable closure such as bung.
It has heretofore been suggested that inserts could be embedded in the wall of a hollow plastic container during the blowing of a preform outwardly against the confines of a mold. Thus, U.S. Pat. No. 4,342,799 shows a hollow body wherein an annular insert is positioned in a blow mold and has openings in the wall thereof such that as the material of the preform is blown outwardly the material penetrates the openings from opposite sides and becomes heat sealed together. In U.S. Pat. No. 4,307,059, a sterile needle puncture site is provided in a blow mold plastic material by positioning a rubber seal in a storage cover which in turn is positioned in the blow mold and the preform is blown outwardly either about or within the rubber seal. The positioning of various inserts or parts on a mold wall so that they become part of the hollow article that is blown is also shown, for example, in U.S. Pat. Nos. 3,705,931 and 3,575,949.
Among the objectives of the present invention are to provide a novel plastic body having an insert in a wall thereof for receiving a closure and a novel method and apparatus for making such an article wherein the insert is effectively locked and held in position and wherein the insert can function for receiving a closure where the hollow body comprises a drum.
In accordance with the invention a hollow thermoplastic container having an annular closure receiving insert embedded in the wall thereof is made by blowing a hollow preform radially outwardly against the confines of a mold wherein a mandrel having a pointed end is positioned on the wall of the mold and supports the insert on the wall of the mold with the point extending inwardly such that as the preform is blown outwardly, the plastic material is deflected and caused to form about the periphery of the insert.